compress-man-pages: don't leak build timestamp into archive (#435295)

Changed files
+1 -1
pkgs
build-support
setup-hooks
+1 -1
pkgs/build-support/setup-hooks/compress-man-pages.sh
···
# Compress all uncompressed manpages. Don't follow symlinks, etc.
# gzip -f is needed to not error out on hard links.
find "$dir"/share/man/ -type f -a '!' -regex '.*\.\(bz2\|gz\|xz\)$' -print0 \
-
| xargs -0 -n1 -P "$NIX_BUILD_CORES" gzip -f
+
| xargs -0 -n1 -P "$NIX_BUILD_CORES" gzip -n -f
# Point symlinks to compressed manpages.
find "$dir"/share/man/ -type l -a '!' -regex '.*\.\(bz2\|gz\|xz\)$' -print0 \